Lots of choices here:
http://www.parts-express.com/cat/subwoofer-plate-amplifiers/332
Note that while the speaker is rated for 170W, the amp was 500W... anything 300W and above is suitable. And BASH is a class of amplifier, not a brand, but they make for good sub amps!
BTW, check speaker impendence or measure DC resistance. You'll have to wire the dual woofers in series or parallel; one raises the impedence, the other lowers it. DCR is usually lower than the impendece, so don't get excited by 3 ohms - it's what you're aiming for in a 4 ohm speaker.
HAve fun,
Frank
